Just did this "mod" myself. Just takes some balls to be willing to pull the top part of the bumper forward (believing you're not going to break it). After that, just requires a little coordination to press in tabs while pulling grill out with enough force.
As said in DIY, once you've done the first one, reach through the open hole and do the second. Plus, you'll know exactly how hard to press/pull.
Best $130 I've spent. Looks great on my Glacier Silver Msport.
'13 335i M-Sport l Glacier Silver l Black l AlumHex l 8AT
retired: '08 335 xi l Silver/Black/Gray Pop l KW v3 l 6AT
retired: '01 Z3 2.5i l Silver l Black l 5MT
retired: '94 325is l Black l Black l 5MT